The forces on the unmanned hypersonic glider tested last summer by the U.S. Defense Advanced Research Projects Agency (DARPA) were so great that large parts of its skin peeled off causing its emergency system to plunge it into the ocean.

As we reported last August, the Falcon HTV-2 "was shot up on a rocket and right at the edge of space, it separated and glided through the atmosphere at 13,000 mph."

The AP reports that over the weekend DARPA said the vehicle reached Mach 20 — a speed 20 time greater than the speed of sound — for three minutes before shockwaves 100 times greater than what the vehicle was designed to withstand started deteriorating the gap of the vehicle's skin.

The AP quotes Air Force Maj. Chris Schulz, the DARPA program manager, as saying:

"The result of these findings is a profound advancement in understanding the areas we need to focus on to advance aerothermal structures for future hypersonic vehicles. Only actual flight data could have revealed this to us."